1. Field of the Invention
This invention relates to integrated circuits (IC's), and more particularly, to controlling the power consumption of IC's.
2. Description of the Related Art
During the design of a computer or other processor-based system, many design factors must be considered. A successful design may require several tradeoffs between power consumption, performance, thermal output, and so forth. For example, the design of a computer system with an emphasis on high performance may allow for greater power consumption and thermal output. Conversely, the design of a portable computer system that is sometimes powered by a battery may emphasize reducing power consumption at the expense of some performance. These same factors may be considered when designing the individual IC's to be used in the computer system.
Two commonly used methods of controlling power consumption are clock-gating and power-gating. When using clock-gating, a clock signal provided to units of an IC may be inhibited or otherwise blocked from reaching those units when utilizing a power saving mode. When power-gating is used, power may be removed from the units of the IC for operations in a power saving mode. Both clock and power-gating are used in some systems. For example, clock-gating may be used to put the units of an IC into an idle state that can quickly be exited by restoring the clock signal. Power-gating may be applied subsequent to clock-gating to place units into a sleep state in which no power or clock is received. Clock and power-gating may be applied to an IC, or multiple IC's, on a coarse or fine-grained basis. On a coarse-grained basis, power and clock-gating are performed for the multiple units of an IC concurrently. On a fine-grained basis, power and clock-gating may be applied to individual state elements and other circuits.